1. Field of the Invention
The present invention relates to a weft yarn extracting device for extracting a picked weft yarn from the cloth fell of a fabric.
2. Description of the Prior Art
When a short pick occurs during weaving, a shortly picked weft yarn is inserted in a shed only in a portion of the entire width of the cloth fell and hence an insufficient beating force acts on a portion of the cloth fell where the weft yarn does not exist. Accordingly, a portion of the weft yarn inserted in the preceding picking cycle and corresponding to the portion of the cloth fell where no weft yarn exists is not beaten satisfactorily. On the other hand, when a weft yarn is inserted in a shed with the leading end thereof doubled back, two weft yarns are extended in a portion of the cloth fell in a double pick mode, so that a portion of a weft yarn inserted in the preceding picking cycle and corresponding to the portion of the cloth fell where the two weft yarns are extended is beaten excessively. Such a faulty weft yarn insertion causes picking barres. Therefore, when a faulty weft insertion occurred, the improperly inserted weft yarn and several weft yarns inserted in the preceding picking cycles must be extracted from the cloth. An inserted weft yarn extracting device is used for the automatic extraction of inserted weft yarns.
Inventions relating to a weft yarn extracting device for such a purpose are disclosed in U.S. Pat. Nos. 4,502,512 and 4,688,606. According to these inventions, a cutting device disposed on the picking side of a loom is held inoperative when a faulty weft yarn insertion occurs to leave the improperly inserted weft yarn extending from the picking nozzle; the improperly inserted weft yarn is then gripped by a gripper, and then the improperly inserted weft yarn is extracted by the gripper. Although such a weft yarn extracting means, as compared with those disclosed in U.S. Pat. Nos. 4,529,010 and 4,503,889, which extract an improperly inserted weft yarn from the cloth fell after cutting the improperly inserted weft yarn off the picking nozzle, is capable of surely catching the improperly inserted weft yarn, it is impossible to extract weft yarns normally inserted in the preceding picking cycles by this weft yarn extracting device, and hence this weft yarn extracting device is unable to deal effectively with the disposal of picking barres caused by an improperly inserted weft yarn.